Hardwood flooring is a $2.4 billion dollar a year industry that has been growing at a rate of more than 10% a year. Hardwood floors represent an excellent value in comparison to other flooring options since they never have to be replaced and have been shown to enhance and even increase the value of the homes in which they are installed.
The current hardwood market consists of two types of products: solid and engineered. Solid flooring is generally ¾″ thick, and, as the name implies, it is made of solid hardwood. This type of product currently represents about 60% of the market or 550,000,000 square feet per year. Solid flooring includes a thick top layer that can be sanded and refinished new again several times. As a result, solid wood floors have been known to last well over 100 years. In addition, solid flooring with its ¾″ thickness adds structural strength to any floor system.
All types of solid flooring react, however, to the presence of moisture. In the dry winter months, moisture leaves the wood causing the floor panels or boards to contract slightly in size, leaving unsightly gaps between each board. In the more humid summer months, the wood expands and with too much moisture, the boards may even cup or buckle. For this reason, solid flooring is not recommended for installation below ground level or directly over a concrete slab.
Solid wood floors are therefore intended for nail-down installation only, leaving a proper expansion area around the perimeter of each board given the instability of the wood. Gluing solid flooring directly to any surface including a sub-floor is not desirable because the adhesive does not allow the wood to move or breathe normally, causing the flooring to distort.
Engineered flooring is made of plywood that has been configured in a cross-ply pattern to make the product more stable by decreasing the amount of expansion and contraction the flooring experiences during changes in humidity from one season to another. This type of hardwood is roughly 40% of the market.
Engineered hardwood has been growing faster than solid hardwood for the last couple of years for several reasons. Recent new home construction has been strongest in the South and West. These markets are predominantly “slab” markets where the houses are built on concrete slabs without a basement underneath. This trend toward slab construction is expected to continue for at least the next decade as the number of retired affluent households moving to these regions of the country increases. Since engineered flooring is thinner and more stable, engineered boards can be glued-down directly to the concrete.
Engineered flooring can also be floated over the concrete or any other type of sub-floor. With this manner of installation, the engineered boards rest on top of the sub-floor and are never secured or fastened to the substrate beneath them. Since the individual boards are glued or otherwise secured to each other and not to the sub-floor, the floor expands and contracts as a whole, leaving no gaps or spaces between pieces. Given the increase in slab construction, engineered hardwood floating systems have grown in popularity. With a floating installation, a moisture barrier can also be placed between the concrete slab and the engineered boards. Not only do such systems offer excellent stability but their high speed of installation represent lower costs to the homeowner.
The move in the industry now is toward glueless floating systems. Specially designed tongue-and-groove interlocking systems allow the boards to be snapped together by compressing one coupling part so that it engages the other. High pressure laminate floors have been converted almost entirely to glueless floating systems over the last 6 years.
Engineered hardwood flooring, like laminate flooring, is, however, not easily repaired. Engineered boards have a thin hardwood surface layer no more than one-eighth of an inch thick. Once this layer goes, so does the floor. Unlike engineered flooring, any wood present above the level plane with solid hardwood floors can be sanded-down to allow the floor to span slight imperfections in the sub-floor. Engineered boards are more expensive than comparable solid flooring and are unavailable in the longer lengths in which solid hardwood boards are made, adding to the time and cost of installation of engineered wood floors. A glueless floating system for solid hardwood flooring, therefore, would be highly desirable in the large and growing hardwood flooring industry.
The dominant system currently in use to float solid flooring uses metal clips fastened to the back of the boards to hold the boards together in groups of three or more. This system is time-consuming and creates gaps between the boards during the heating/low humidity season. In addition, the technicians who install ¾″ solid flooring prefer to work from a standing position. Installers therefore resist using the clip system because it requires a different installation technique than the one to which they are accustomed. Since most installers are paid by the foot, they will naturally embrace that technique at which they are the fastest and most effective.
Moreover, solid hardwood flooring is unable to utilize the interlocking technology found on engineered and laminate flooring for a number of reasons. The ¾″ solid flooring boards are not straight enough to engage the entire edge at one time. This is required with certain tongue-and-groove systems where one coupling element must be engaged by the other at an angle and then rotated into position. Solid hardwood has what is referred to as a “crook” or warp. Thus, the flooring must be engaged at one end of the edge first, the remaining portion of the board being engaged as the installer moves along the length of the board. Any locking system for achieving a floating installation of solid hardwood floors must therefore be capable of being engaged in a direct, i.e., horizontal, manner where the engagement is by one section of a given edge at a time.
The present interlocking systems also create waste on both the tongue and groove sides of the board. Milling the profile of the individual coupling elements can consume over 10% of the panel itself. In addition, there is loss of the full face of each floor board, requiring an overlap of the boards and a reduction of the amount of usable product. This is not critical when the substrate is inexpensive plywood or fiberboard. When expensive hardwood is being used, however, the financial ramifications are significant. It is very important when making alterations to or otherwise working with an expensive material such as hardwood so as to create an interlocking structure that as little of the material be used as possible.
As explained above, solid hardwood flooring is also far less dimensionally stable than plywood or fiberboard. Even slight dimensional changes in the profile of the interlocking structures presently found in the prior art that arise due to such factors as a change in humidity has the potential of rendering the intended system of securing one board with another entirely useless.
Moreover, some current interlocking systems developed for the laminate industry have profiles where a tongue with protrusions is forced into a groove that is narrower than the height of these protrusions. These systems will not work with solid hardwood flooring because the shoulders of the groove become fractured as the tongue is forced into position. These fractures can be seen on the finished flooring since the fracture is telegraphed to the exposed upper surface. In fact, even with the high pressure laminate flooring, most of these systems where the groove is forced to open wider in order to accept the tongue have been found to fail in actual practice.
There is a significant need, therefore, for an improved locking system for mechanically joining panels that would allow solid hardwood flooring to be installed in a floating manner over a wide variety of sub-floor surfaces including concrete slabs. A locking system that accomplishes this without the need for fasteners such as nails or glue and other adhesives to hold the boards together would be even more highly desirable. This invention meets those needs and overcomes the above problems and shortcomings in the present art in a simple and inexpensive manner.